Used to place a new pair of control points.

The resulting pair of control points then displays in the control points list box in the Register dialog box, with the status set to on. The pair is inserted just after the previously selected line and the new line is now selected (highlighted). If Dynamic Warping in Views Displaying Uncorrected Data is on, the model updates and the base vector data warping updates in the specified views.

After a model is updated, the distance between the two corresponding marks reveals the residual for this pair of control points. As long as there are no extra points, the model is exact, i.e., there is no residual. Consequently, the two corresponding marks of each pair coincide.